CE562 Lecture 20 Local Roads and Streets

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CE562 Lecture 20 Local Roads and Streets
Text A Policy on Geometric Design, Local Roads
and Streets, 379-416.
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Local Rural Roads

• Design traffic volume is an average daily traffic
  (ADT) predicted for 20 year time horizon or
  shorter depending on the nature of the
  improvement.

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Local Rural Roads
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Local Rural Roads
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Local Rural Roads
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Local Rural Roads
Maximum superelevation 8 (12) See Chapter 3 for
details
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Local Rural Roads Minimum Width of Traveled Way
and Graded Shoulder
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Local Rural Roads
Number of lanes Two travel lanes is a typical
number. More lanes may be provided if justified
by traffic and specific area. Vertical
clearance at least 4.3 m with allowance for
future resurfacing (0.15-0.20 m). Foreslopes
Depends on the stability of local soil, but
should not be steeper than 12. The ditch bottom
and slopes should be well-rounded. Horizontal
clearance to obstructions a clear zone of 2-3 m
should be provided where possible, otherwise
guardrail protection. Curbs Use is limited on
intermediate and high-speed local
roads. Intersection design in Chapter 9. Sight
distance in Chapter 3.
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Local Urban Streets

• More restrictions than in rural areas
• type and extent of land development
• regulatory restrictions
• Residential areas
• Safety and pleasant environment are more
  important than the convenience of motorists.
• Industrial and commercial areas
• Vehicle dimensions, traffic volumes, and vehicle
  loads are predominant design factors.

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Local Urban Streets

• Design traffic volume is an AADT projected for at
  least 10 years and preferably 20 years.
• Design speed 30-50 km/h due to closely spaced
  intersections.
• Sight distance 30-60 m for stopping
• Grades
• Residential streets should be consistent with
  terrain maximum grade is 15.
• Commercial and industrial streets should have
  gradient lower than 8 (desirably less than 5).
• Minimum gradient is 0.2-0.3 for curbed streets
  (drainage consideration).

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Local Urban Streets

• Horizontal alignment in residential areas
• should fit closely the topography
• should discourage through traffic
• Horizontal alignment in commercial and industrial
  areas
• should be commensurate with the topography
• but should be as direct as possible
• Minimum radius is 30 m (exceptionally 25 m).
• Cross slope see the general guidelines

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Local Urban Streets

• Superelevation usually is not provided on
  residential and commercial streets, but should be
  considered in industrial areas. Maximum
  superelevation is 4 (6 allowed if justified).
• Number of lanes
• On residential streets where single-family units
  prevail, at least one 3.6 m wide travel way with
  2.2 m wide parking lanes on both sides (total 8
  m).
• On residential streets where multifamily unites
  prevails, two travel lanes are usually needed.
• On commercial streets two lanes are needed. An
  additional continuous two-way left-turn lane
  should be considered.

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Local Urban Streets

• Width of roadway
• Moving lanes should be at least 3.0 m, where
  feasible - 3.3 m, in industrial areas - 3.6 m.
• Where severe limitations are imposed, 2.7 m wide
  lanes can be used in residential areas, and 3.3 m
  wide lanes in industrial areas.
• Additional turning lanes should be at least 2.7 m
  wide, preferably 3.0-3.6 wide depending on the
  percentages of trucks.
• Parallel parking lanes should be at least 2.2 m
  wide in residential areas, and 2.7 m wide in
  commercial and industrial areas.
• Curbs Streets are curbed. Steep-face curbs 15 cm
  or higher should be offset from the moving lanes
  at least 0.3 m without gutter, and 0.6 m with
  gutter.

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Local Urban Streets Cul-de-sacs and dead ends
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Local Urban Streets Alleys
Should be 5-6 m wide in residential areas, and
up to 10 m in industrial areas.
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Local Urban Streets

• Horizontal clearance to obstruction at least 0.5
  m from the curb face. Trees adjacent to curbed
  streets allowed for speed 60 km/h or less.
• Vertical clearance 4.3 m with allowance for
  future resurfacing.
• Border area and sidewalks the minimum border
  width is 1.5 m, preferably 3.0 m. The sidewalk
  width 1.2 or 2.4 m typically. In commercial areas
  may be wider. A 3.6 m separation from the street
  is preferred.
• Intersections
• sight requirements see Chapter 9
• angle 90 degrees preferable and at least 60
  degrees
• grades on approaches should not exceed 5 0.5-2
  grades as maximum are recommended where snow and
  ice is possible
• in residential areas, corner radius should be at
  least 7.5 m
• in industrial areas, the curb return should not
  be less than 10 m, and desirable should be made
  of a three-centered curve

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Recreational Roads
Exhibit 5-12
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Recreational Roads

• Design speed
• primary access roads - 60 km/h
• circulation roads - 50 km/h
• area roads - 30 km/h
• Design vehicle motor homes, vehicle with
  trailer, and passenger car
• Other design details regarding
• passing sight distance
• grades
• alignment
• number of lanes, widths of traveled way,
  shoulder, and roadway
• turnout design, etc.
• are provided in the section Local Roads and
  Streets.

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Recreational Roads
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Recreational Roads
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Recreational Roads
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Recreational Roads
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Additional Sources

• 1. AASHTO. Guide for the Development of Bicycle
  Facilities, Washington, D.C.AASHTO, 1999.
• 2. AASHTO. Standard Specifications for Highway
  Bridges, Washington, D.C. AASHTO, 1996.
• 3. AASHTO. Roadside Design Guide, Washington,
  D.C. AASHTO, 1996, or more recent edition.
• 4. U.S. Department of Transportation, Federal
  Highway Administration. Manual on Uniform Traffic
  Control Devices for Streets and Highways,
  Washington, D.C. 1988 or most current edition.
• 5. AASHTO. Guide for the Planning, Design, and
  Operation of Pedestrian Facilities, Washington,
  D.C. AASHTO, forthcoming.
• 6. Bert, K. E., et al. Accommodation of Utility
  Plants Within the Rights-of- Way of Urban Streets
  and Highways, Manual of Improved Practice, ASCE
  Manual No. 14. Chicago American Public Works
  Association, and New York American Society of
  Civil Engineers, July 1974.
• 7. AASHTO. Guide for Accommodating Utilities on
  Highway Rights-of-Way, Washington, D.C. AASHTO,
  1994.
• 8. AASHTO. An Informational Guide for Roadway
  Lighting, Washington, D.C. AASHTO, 1984.
• 9. AASHTO. A Guide for Transportation Landscape
  and Environmental Design, Washington, D.C.,
  AASHTO, 1991.